Heroin can be taken through a hypodermic needle which is illegal in the States without a prescription. It can also be snorted or smoked. It can also be inhaled by lighting the heroin in powder form and fumes are inhaled through a tube. Other methods of using heroin are:

Skin popping: injecting into a muscle and under the skin at the same time

Mainlining: injecting straight into the veins

Since heroin mostly comes in a powder form it is melted by putting it on a spoon, then lighting it to make a liquid then put into a needle.

Needles are usually injected into the arm or if the user wants the needle scars to be hidden, inbetween toes.